Methods for handling pyrolysis oil

Abstract

A method of maintaining the stability of pyrolysis oil by removing oxygen from the pyrolysis oil and / or preventing or reducing the instances where oxygen come into contact with the pyrolysis oil. The method comprises removing oxygen, by a physical process, from the pyrolysis oil.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of European Patent Application No. 22216309.9, filed Dec. 23, 2022, which is hereby incorporated by reference in its entirety.FIELD OF INVENTION

[0002] The present invention generally relates to the handling of pyrolysis oil. More specifically, the present invention is related to maintaining the stability and the quality of pyrolysis oil by reducing the amount of oxygen in contact with the pyrolysis oil.BACKGROUND OF THE INVENTION

[0003] Chemical recycling of mixed plastic waste is used to produce pyrolysis oil (pyoil), which is emerging as a significant alternative feedstock for producing olefins and aromatics. But pyrolysis oil is very unstable and can rapidly form gum when it is being transported or stored. Classical antioxidants, which were thought to be effective in stabilizing pyrolysis oil, have been found not to be very effective. As a result of the instability of pyrolysis oil and the lack of effective antioxidants to maintain its stability, the longer pyrolysis oil is stored, the lower its quality becomes as a feedstock.BRIEF SUMMARY OF THE INVENTION

[0004] The instability of pyrolysis oil is, at least in part, due to the ease with which compounds of the pyrolysis oil react with each other or with other materials. For example, oxygen or nitrogenates resident in the pyrolysis oil from the chemical recycling process and / or oxygen or nitrogenates that come in contact with the pyrolysis oil during storage and / or transportation can result in chemical reactions that form other compounds and thereby lower the quality of the pyrolysis oil as a feedstock. The present inventors have discovered a method of maintaining the stability of pyrolysis oil by removing oxygen from the pyrolysis oil and / or preventing or reducing the instances where oxygen come into contact with the pyrolysis oil.

[0005] Embodiments of the invention include a method of maintaining pyrolysis oil stability and / or improving quality. The method comprises removing oxygen, by a physical process, from the pyrolysis oil. In the method, the physical process can involve flowing an inert gas through the pyrolysis oil to remove the oxygen from the pyrolysis oil or placing the pyrolysis oil under vacuum.

[0006] Embodiments of the invention include a method of maintaining pyrolysis oil stability and / or quality. The method includes providing a tank for storing pyrolysis oil. The method further includes removing oxygen from the tank. Further yet, the method includes flowing pyrolysis oil into the tank and storing the pyrolysis oil in the tank.

[0007] Embodiments of the invention include a method of maintaining pyrolysis oil stability and / or quality. The method includes storing the pyrolysis oil in a tank and removing oxygen from headspace of the tank.

[0008] The following includes definitions of various terms and phrases used throughout this specification.

[0009] The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment the terms are defined to be within 10%, preferably, within 5%, more preferably, within 1%, and most preferably, within 0.5%.

[0010] For the purposes of this disclosure, “X, Y, and / or Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XY, XZ, YZ).

[0011] The terms “wt. %”, “vol. %” or “mol. %” refer to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume, or the total moles of material that includes the component. In a non-limiting example, 10 moles of component in 100 moles of the material are 10 mol. % of component.

[0012] The term “substantially” and its variations are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

[0013] The terms “inhibiting” or “reducing” or “preventing” or “avoiding” or any variation of these terms, when used in the claims and / or the specification, include any measurable decrease or complete inhibition to achieve a desired result.

[0014] The term “effective,” as that term is used in the specification and / or claims, means adequate to accomplish a desired, expected, or intended result.

[0015] The use of the words “a” or “an” when used in conjunction with the term “comprising,”“including,”“containing,” or “having” in the claims or the specification may mean “one,” but it is also consistent with the meaning of “one or more,”“at least one,” and “one or more than one.”

[0016] The words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0017] The process of the present invention can “comprise,”“consist essentially of,” or “consist of” particular ingredients, components, compositions, etc., disclosed throughout the specification.

[0018] The term “primarily,” as that term is used in the specification and / or claims, means greater than any of 50 wt. %, 50 mol. %, and 50 vol. %. For example, “primarily” may include 50.1 wt. % to 100 wt. % and all values and ranges there between, 50.1 mol. % to 100 mol. % and all values and ranges there between, or 50.1 vol. % to 100 vol. % and all values and ranges there between.

[0019] Other objects, features and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] For a more complete understanding, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0021] FIG. 1A and FIG. 1B show systems for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention;

[0022] FIG. 2 shows a method for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention;

[0023] FIG. 3 shows a method for maintaining pyrolysis oil stability and / or quality according to embodiments of the invention;

[0024] FIG. 4 shows a method for maintaining pyrolysis oil stability and / or quality according to embodiments of the invention;

[0025] FIG. 5A, FIG. 5B, and FIG. 5C show results of an experiment to show how certain factors affect gum formation; and

[0026] FIG. 6 shows results of an experiment to show how certain factors affect gum formation.DETAILED DESCRIPTION OF THE INVENTION

[0027] After pyrolysis oil is formed by chemical recycling of mixed plastic waste, it is susceptible to deterioration as a result of the presence of oxygen in or in contact with the pyrolysis oil. The oxygen reacts with particular components of the pyrolysis oil to form gum. Gum reduces the quality of pyrolysis oil and induces product losses due to significant deposit during transport or storage of the pyrolysis oil. Thus, embodiments of the invention involve purging the pyrolysis oil gas phase or bulk with nitrogen or any other inert gas to remove oxygen from the pyrolysis oil itself and / or from a tank in which the pyrolysis oil is stored or is to be stored.

[0028] FIG. 1A shows system 10A for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention. FIG. 1B shows system 10B for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention. FIG. 2 shows method 20 for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention. FIG. 3 shows method 30 for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention. FIG. 4 shows method 40 for maintaining pyrolysis oil stability and / or quality according to embodiments of the invention. In embodiments of the invention, method 20 may be implemented by system 10A. In embodiments of the invention, method 30 may be implemented by system 10B. In embodiments of the invention, method 40 may be implemented by system 10B.Systems for Maintaining Pyrolysis Oil Stability and / or Quality

[0029] System 10A, according to embodiments of the invention, comprises tank 101, which is adapted to store pyrolysis oil 100. In embodiments of the invention, system 10A includes compressor 103 for flowing inert gas 102 through tank 101 and thereby through pyrolysis oil 100 (when in storage in tank 101), where inert gas 102 and oxygen exit tank 101 as effluent 104.

[0030] System 10B, according to embodiments of the invention, comprises tank 101, which is adapted to store pyrolysis oil 100. In embodiments of the invention, system 10B includes compressor 106 for removing gas (e.g., air and / or oxygen) from tank 101 or headspace 105 of tank 101. In the absence of any, or a significant amount of, oxygen in tank 101 or headspace 105, pyrolysis oil 100 can be stored in tank 101 away from or in minimal contact with oxygen, according to embodiments of the invention. System 10B includes pump 107 for pumping pyrolysis oil 100 into tank 101, in embodiments of the invention. System 10B, according to embodiments of the invention, includes compressor 103 for flowing inert gas 102 through tank 101 and thereby through pyrolysis oil 100 (when in storage in tank 101), where inert gas 102 and oxygen exit tank 101 as effluent 104 or are removed by compressor 106.Methods of Maintaining Pyrolysis Oil Stability and / or Quality

[0031] Method 20, as implemented using system 10A, according to embodiments of the invention, include, at block 200, storing pyrolysis oil 100 in tank 101. Block 201 of method 20, in embodiments of the invention, includes flowing inert gas 102 through pyrolysis oil 100, via compression by compressor 103 (as shown in FIG. 1A), to remove oxygen from pyrolysis oil 100. According to embodiments of the invention, the removal of the oxygen is carried out by a physical process effected by the flowing of inert gas 102 through pyrolysis oil 100. Inert gas 102, in embodiments of the invention, comprises any of: nitrogen, helium, argon, neon, carbon dioxide, and any combination thereof. According to embodiments of the invention, when inert gas 102 is being flowed through pyrolysis oil 100, pyrolysis oil 100 is at a temperature in the range of 20° C. to 70° C., including ranges of 20 to 25° C., 25 to 30° C., 30 to 35° C., 35 to 40° C., 40 to 45° C., 45 to 50° C., 50 to 55° C., 55 to 60° C., 60 to 65° C., and 65 to 70° C. According to embodiments of the invention, method 20 includes block 202, which involves flowing effluent 104 (comprising oxygen and inert gas (e.g., nitrogen)) from tank 101.

[0032] Method 30, as implemented using system 10B, according to embodiments of the invention, includes, at block 300, providing tank 101 for storing pyrolysis oil. Block 301, of method 30, includes removing gas (e.g., air and / or oxygen) from tank 101 (as shown in FIG. 1B), in embodiments of the invention. According to embodiments of the invention, the removing of gas (e.g., air and / or oxygen), at block 301, can involve extracting the gas (or at least some of it) with compressor 106 and / or flowing inert gas 102 into tank 101. At block 302, according to embodiments of the invention, pump 107 pumps pyrolysis oil 100 into tank 101 to occupy all the space in tank 101 or some of the space and thus forming headspace 105. With pyrolysis oil 100 occupying all or most of tank 101 and / or inert gas primarily or totally occupying headspace 105, there is a minimal amount of (or no) oxygen in contact with the pyrolysis oil and thus there is insufficient oxygen to make pyrolysis oil 100 unstable and to deteriorate its quality. According to embodiments of the invention, as a result of method 30, the oxygen concentration in tank 101 is reduced to 0.01% to 1%.

[0033] In embodiments of the invention, before or after implementation of method 30 to remove oxygen from tank 101, method 20 can be implemented to remove oxygen from pyrolysis oil 100.

[0034] Method 40, as implemented using system 10B, according to embodiments of the invention, includes, at block 400, storing pyrolysis oil 100 in tank 101. Block 401, of method 40, includes compressor 106 removing gas (e.g., air and / or oxygen) from headspace 105 of tank 101. In the absence of any or a significant amount of oxygen in headspace 105, pyrolysis oil 100 is less susceptible to instability and deterioration in quality.

[0035] In embodiments of the invention, before or after implementation of method 40 to remove oxygen from headspace 105 of tank 101, method 20 can be implemented to remove oxygen from pyrolysis oil 100.

[0036] Although embodiments of the present invention have been described with reference to blocks of FIG. 2, FIG. 3, and FIG. 4 it should be appreciated that operation of the present invention is not limited to the particular blocks and / or the particular order of the blocks illustrated in FIG. 2, FIG. 3, and FIG. 4. Accordingly, embodiments of the invention may provide functionality as described herein using various blocks in a sequence different than that of FIG. 2, FIG. 3, and FIG. 4.

[0037] The systems and processes described herein can also include various equipment that is not shown and is known to one of skill in the art of chemical processing. For example, some controllers, piping, computers, valves, pumps, heaters, thermocouples, pressure indicators, mixers, heat exchangers, and the like may not be shown.

[0038] As part of the disclosure of the present invention, specific examples are included below. The examples are for illustrative purposes only and are not intended to limit the invention. Those of ordinary skill in the art will readily recognize parameters that can be changed or modified to yield essentially the same results.ExampleAgeing Study of Pyoil Samples

[0039] Six liter samples of pyrolysis oil were collected in pre-filled nitrogen bottles. Some samples were purged with nitrogen.Density

[0040] Density was measured on the samples at time 0, i.e., after sample preparation was completed. The data as shown in Table 1 indicates that the purging step leads to an increase of the density of the pyoil. This is because volatile constituents are being stripped, to a certain extent, from the sample during the purge.TABLE 1Density of pure and purged samplesMeasure-Measure-Measure-ment 1ment 2ment 3averagestdevDensity of Pure0.790570.790630.790610.790600.00003sample 0 days[g / ml]Density Purged0.792200.792080.792150.792140.00006sample 0 days[g / ml]Gums Kinetic Formation

[0041] Sixteen vials were prepared in order to follow the gum kinetic formation. Eight vials were purged with nitrogen and eight vials were not purged. The goal was to measure the amount of gum formed after 10, 20 and 60 days. The pure samples were poured from the received Schott bottles into the small vials with no treatment. The purged samples were purged with nitrogen for 5 minutes. The vials were then closed, and paraffin film was used. At each data point time, the supernatant of the vials was emptied. The vials were left to dry in a fume hood overnight. The day after, 10 mL of tetrahydrofuran (THF) was added to the vial to solubilize the gums formed during the ageing process. The THF was then poured into pre-weighted alumina pans. THF was evaporated overnight in a fume hood. Finally, the pans were placed in a vacuum oven at 40° C. to completely remove volatiles. The gums amount formed during the ageing process at each condition was then defined by weighing the dried alumina pans.

[0042] The weight of the gum was then fitted in JMP (statistical software) to study the impact of the following factors: Type of glass (amber, transparent), Time of ageing (8, 15, 26 and 48 days), Type of treatment (pure and purged).

[0043] FIG. 5A, FIG. 5B, and FIG. 5C indicate that ageing time and treatment have a significant impact on the amount of gum being formed (P<0.05).

[0044] FIG. 6 indicates that the amount of gum increases with increased ageing time and is higher for the pure samples. The factor “type of glass” is borderline significant with a p value of 0.052.

[0045] Based on this specific ageing study, it can be concluded that gum formation is favored when the sample is not purged with nitrogen. Light also seems to increase the gum's formation rate.

[0046] In the context of the present invention, at least the following 14 embodiments are described. Embodiment 1 is a method of maintaining pyrolysis oil stability and / or quality. The method includes removing oxygen, by a physical process, from pyrolysis oil. Embodiment 2 is the method of embodiment 1, wherein the physical process comprises flowing an inert gas through the pyrolysis oil. Embodiment 3 is the method of embodiment 2, wherein the inert gas comprises: nitrogen, helium, argon, neon, carbon dioxide or combinations thereof. Embodiment 4 is the method of any of embodiments 1 to 4, wherein the pyrolysis oil is at a temperature of 20° C. to 70° C.

[0047] Embodiment 5 is a method of maintaining pyrolysis oil stability and / or quality. The method includes providing a tank for storing pyrolysis oil. The method further includes removing oxygen from the tank. The method yet further includes flowing pyrolysis oil into the tank and storing the pyrolysis oil in the tank. Embodiment 6 is the method of embodiment 5, wherein the removing of the oxygen from the tank comprises displacement with an inert gas and / or extraction with a compressor. Embodiment 7 is the method of either of embodiments 5 or 6, wherein the oxygen concentration in the tank is reduced to 0.01% to 1%. Embodiment 8 is the method of any of embodiments 5 to 7, further comprising flowing an inert gas through the pyrolysis oil to remove oxygen from the pyrolysis oil. Embodiment 9 is the method of embodiment 8, wherein the inert gas comprises: nitrogen, helium, argon, neon, carbon dioxide or combinations thereof. Embodiment 10 is the method of either of embodiments 8 or 9, wherein the pyrolysis oil is at a temperature of 20° C. to 70° C.

[0048] Embodiment 11 is a method of maintaining pyrolysis oil stability and / or quality. The method includes storing pyrolysis oil in a tank. The method further includes removing oxygen from headspace of the tank. Embodiment 12 is the method of embodiment 11, wherein the removing of the oxygen from the headspace of the tank comprises extraction by a compressor. Embodiment 13 is the method of either of embodiments 11 or 12, wherein the oxygen concentration in the tank is reduced to 0.01% to 1%. Embodiment 14 is the method of any of embodiments 11 to 13 further comprising flowing an inert gas through the pyrolysis oil to remove oxygen from the pyrolysis oil.

[0049] The systems and processes described herein can also include various equipment that is not shown and is known to one of skill in the art of chemical processing. For example, some controllers, piping, computers, valves, pumps, heaters, thermocouples, pressure indicators, mixers, heat exchangers, and the like may not be shown. All embodiments described above and herein can be combined in any manner unless expressly excluded.

[0050] Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the above disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Examples

example

Ageing Study of Pyoil Samples

[0039]Six liter samples of pyrolysis oil were collected in pre-filled nitrogen bottles. Some samples were purged with nitrogen.

Density

[0040]Density was measured on the samples at time 0, i.e., after sample preparation was completed. The data as shown in Table 1 indicates that the purging step leads to an increase of the density of the pyoil. This is because volatile constituents are being stripped, to a certain extent, from the sample during the purge.

TABLE 1Density of pure and purged samplesMeasure-Measure-Measure-ment 1ment 2ment 3averagestdevDensity of Pure0.790570.790630.790610.790600.00003sample 0 days[g / ml]Density Purged0.792200.792080.792150.792140.00006sample 0 days[g / ml]

Gums Kinetic Formation

[0041]Sixteen vials were prepared in order to follow the gum kinetic formation. Eight vials were purged with nitrogen and eight vials were not purged. The goal was to measure the amount of gum formed after 10, 20 and 60 days. The pure samples were poured fro...

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of European Patent Application No. 22216309.9, filed Dec. 23, 2022, which is hereby incorporated by reference in its entirety.FIELD OF INVENTION

[0002] The present invention generally relates to the handling of pyrolysis oil. More specifically, the present invention is related to maintaining the stability and the quality of pyrolysis oil by reducing the amount of oxygen in contact with the pyrolysis oil.BACKGROUND OF THE INVENTION

[0003] Chemical recycling of mixed plastic waste is used to produce pyrolysis oil (pyoil), which is emerging as a significant alternative feedstock for producing olefins and aromatics. But pyrolysis oil is very unstable and can rapidly form gum when it is being transported or stored. Classical antioxidants, which were thought to be effective in stabilizing pyrolysis oil, have been found not to be very effective. As a result of the instability of pyrolysis oil and the lack of effective antioxidants to maintain its stability, the longer pyrolysis oil is stored, the lower its quality becomes as a feedstock.BRIEF SUMMARY OF THE INVENTION

[0004] The instability of pyrolysis oil is, at least in part, due to the ease with which compounds of the pyrolysis oil react with each other or with other materials. For example, oxygen or nitrogenates resident in the pyrolysis oil from the chemical recycling process and / or oxygen or nitrogenates that come in contact with the pyrolysis oil during storage and / or transportation can result in chemical reactions that form other compounds and thereby lower the quality of the pyrolysis oil as a feedstock. The present inventors have discovered a method of maintaining the stability of pyrolysis oil by removing oxygen from the pyrolysis oil and / or preventing or reducing the instances where oxygen come into contact with the pyrolysis oil.

[0005] Embodiments of the invention include a method of maintaining pyrolysis oil stability and / or improving quality. The method comprises removing oxygen, by a physical process, from the pyrolysis oil. In the method, the physical process can involve flowing an inert gas through the pyrolysis oil to remove the oxygen from the pyrolysis oil or placing the pyrolysis oil under vacuum.

[0006] Embodiments of the invention include a method of maintaining pyrolysis oil stability and / or quality. The method includes providing a tank for storing pyrolysis oil. The method further includes removing oxygen from the tank. Further yet, the method includes flowing pyrolysis oil into the tank and storing the pyrolysis oil in the tank.

[0007] Embodiments of the invention include a method of maintaining pyrolysis oil stability and / or quality. The method includes storing the pyrolysis oil in a tank and removing oxygen from headspace of the tank.

[0008] The following includes definitions of various terms and phrases used throughout this specification.

[0009] The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment the terms are defined to be within 10%, preferably, within 5%, more preferably, within 1%, and most preferably, within 0.5%.

[0010] For the purposes of this disclosure, “X, Y, and / or Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XY, XZ, YZ).

[0011] The terms “wt. %”, “vol. %” or “mol. %” refer to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume, or the total moles of material that includes the component. In a non-limiting example, 10 moles of component in 100 moles of the material are 10 mol. % of component.

[0012] The term “substantially” and its variations are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

[0013] The terms “inhibiting” or “reducing” or “preventing” or “avoiding” or any variation of these terms, when used in the claims and / or the specification, include any measurable decrease or complete inhibition to achieve a desired result.

[0014] The term “effective,” as that term is used in the specification and / or claims, means adequate to accomplish a desired, expected, or intended result.

[0015] The use of the words “a” or “an” when used in conjunction with the term “comprising,”“including,”“containing,” or “having” in the claims or the specification may mean “one,” but it is also consistent with the meaning of “one or more,”“at least one,” and “one or more than one.”

[0016] The words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0017] The process of the present invention can “comprise,”“consist essentially of,” or “consist of” particular ingredients, components, compositions, etc., disclosed throughout the specification.

[0018] The term “primarily,” as that term is used in the specification and / or claims, means greater than any of 50 wt. %, 50 mol. %, and 50 vol. %. For example, “primarily” may include 50.1 wt. % to 100 wt. % and all values and ranges there between, 50.1 mol. % to 100 mol. % and all values and ranges there between, or 50.1 vol. % to 100 vol. % and all values and ranges there between.

[0019] Other objects, features and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] For a more complete understanding, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0021] FIG. 1A and FIG. 1B show systems for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention;

[0022] FIG. 2 shows a method for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention;

[0023] FIG. 3 shows a method for maintaining pyrolysis oil stability and / or quality according to embodiments of the invention;

[0024] FIG. 4 shows a method for maintaining pyrolysis oil stability and / or quality according to embodiments of the invention;

[0025] FIG. 5A, FIG. 5B, and FIG. 5C show results of an experiment to show how certain factors affect gum formation; and

[0026] FIG. 6 shows results of an experiment to show how certain factors affect gum formation.DETAILED DESCRIPTION OF THE INVENTION

[0027] After pyrolysis oil is formed by chemical recycling of mixed plastic waste, it is susceptible to deterioration as a result of the presence of oxygen in or in contact with the pyrolysis oil. The oxygen reacts with particular components of the pyrolysis oil to form gum. Gum reduces the quality of pyrolysis oil and induces product losses due to significant deposit during transport or storage of the pyrolysis oil. Thus, embodiments of the invention involve purging the pyrolysis oil gas phase or bulk with nitrogen or any other inert gas to remove oxygen from the pyrolysis oil itself and / or from a tank in which the pyrolysis oil is stored or is to be stored.

[0028] FIG. 1A shows system 10A for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention. FIG. 1B shows system 10B for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention. FIG. 2 shows method 20 for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention. FIG. 3 shows method 30 for maintaining pyrolysis oil stability and / or quality, according to embodiments of the invention. FIG. 4 shows method 40 for maintaining pyrolysis oil stability and / or quality according to embodiments of the invention. In embodiments of the invention, method 20 may be implemented by system 10A. In embodiments of the invention, method 30 may be implemented by system 10B. In embodiments of the invention, method 40 may be implemented by system 10B.Systems for Maintaining Pyrolysis Oil Stability and / or Quality

[0029] System 10A, according to embodiments of the invention, comprises tank 101, which is adapted to store pyrolysis oil 100. In embodiments of the invention, system 10A includes compressor 103 for flowing inert gas 102 through tank 101 and thereby through pyrolysis oil 100 (when in storage in tank 101), where inert gas 102 and oxygen exit tank 101 as effluent 104.

[0030] System 10B, according to embodiments of the invention, comprises tank 101, which is adapted to store pyrolysis oil 100. In embodiments of the invention, system 10B includes compressor 106 for removing gas (e.g., air and / or oxygen) from tank 101 or headspace 105 of tank 101. In the absence of any, or a significant amount of, oxygen in tank 101 or headspace 105, pyrolysis oil 100 can be stored in tank 101 away from or in minimal contact with oxygen, according to embodiments of the invention. System 10B includes pump 107 for pumping pyrolysis oil 100 into tank 101, in embodiments of the invention. System 10B, according to embodiments of the invention, includes compressor 103 for flowing inert gas 102 through tank 101 and thereby through pyrolysis oil 100 (when in storage in tank 101), where inert gas 102 and oxygen exit tank 101 as effluent 104 or are removed by compressor 106.Methods of Maintaining Pyrolysis Oil Stability and / or Quality

[0031] Method 20, as implemented using system 10A, according to embodiments of the invention, include, at block 200, storing pyrolysis oil 100 in tank 101. Block 201 of method 20, in embodiments of the invention, includes flowing inert gas 102 through pyrolysis oil 100, via compression by compressor 103 (as shown in FIG. 1A), to remove oxygen from pyrolysis oil 100. According to embodiments of the invention, the removal of the oxygen is carried out by a physical process effected by the flowing of inert gas 102 through pyrolysis oil 100. Inert gas 102, in embodiments of the invention, comprises any of: nitrogen, helium, argon, neon, carbon dioxide, and any combination thereof. According to embodiments of the invention, when inert gas 102 is being flowed through pyrolysis oil 100, pyrolysis oil 100 is at a temperature in the range of 20° C. to 70° C., including ranges of 20 to 25° C., 25 to 30° C., 30 to 35° C., 35 to 40° C., 40 to 45° C., 45 to 50° C., 50 to 55° C., 55 to 60° C., 60 to 65° C., and 65 to 70° C. According to embodiments of the invention, method 20 includes block 202, which involves flowing effluent 104 (comprising oxygen and inert gas (e.g., nitrogen)) from tank 101.

[0032] Method 30, as implemented using system 10B, according to embodiments of the invention, includes, at block 300, providing tank 101 for storing pyrolysis oil. Block 301, of method 30, includes removing gas (e.g., air and / or oxygen) from tank 101 (as shown in FIG. 1B), in embodiments of the invention. According to embodiments of the invention, the removing of gas (e.g., air and / or oxygen), at block 301, can involve extracting the gas (or at least some of it) with compressor 106 and / or flowing inert gas 102 into tank 101. At block 302, according to embodiments of the invention, pump 107 pumps pyrolysis oil 100 into tank 101 to occupy all the space in tank 101 or some of the space and thus forming headspace 105. With pyrolysis oil 100 occupying all or most of tank 101 and / or inert gas primarily or totally occupying headspace 105, there is a minimal amount of (or no) oxygen in contact with the pyrolysis oil and thus there is insufficient oxygen to make pyrolysis oil 100 unstable and to deteriorate its quality. According to embodiments of the invention, as a result of method 30, the oxygen concentration in tank 101 is reduced to 0.01% to 1%.

[0033] In embodiments of the invention, before or after implementation of method 30 to remove oxygen from tank 101, method 20 can be implemented to remove oxygen from pyrolysis oil 100.

[0034] Method 40, as implemented using system 10B, according to embodiments of the invention, includes, at block 400, storing pyrolysis oil 100 in tank 101. Block 401, of method 40, includes compressor 106 removing gas (e.g., air and / or oxygen) from headspace 105 of tank 101. In the absence of any or a significant amount of oxygen in headspace 105, pyrolysis oil 100 is less susceptible to instability and deterioration in quality.

[0035] In embodiments of the invention, before or after implementation of method 40 to remove oxygen from headspace 105 of tank 101, method 20 can be implemented to remove oxygen from pyrolysis oil 100.

[0036] Although embodiments of the present invention have been described with reference to blocks of FIG. 2, FIG. 3, and FIG. 4 it should be appreciated that operation of the present invention is not limited to the particular blocks and / or the particular order of the blocks illustrated in FIG. 2, FIG. 3, and FIG. 4. Accordingly, embodiments of the invention may provide functionality as described herein using various blocks in a sequence different than that of FIG. 2, FIG. 3, and FIG. 4.

[0037] The systems and processes described herein can also include various equipment that is not shown and is known to one of skill in the art of chemical processing. For example, some controllers, piping, computers, valves, pumps, heaters, thermocouples, pressure indicators, mixers, heat exchangers, and the like may not be shown.

[0038] As part of the disclosure of the present invention, specific examples are included below. The examples are for illustrative purposes only and are not intended to limit the invention. Those of ordinary skill in the art will readily recognize parameters that can be changed or modified to yield essentially the same results.ExampleAgeing Study of Pyoil Samples

[0039] Six liter samples of pyrolysis oil were collected in pre-filled nitrogen bottles. Some samples were purged with nitrogen.Density

[0040] Density was measured on the samples at time 0, i.e., after sample preparation was completed. The data as shown in Table 1 indicates that the purging step leads to an increase of the density of the pyoil. This is because volatile constituents are being stripped, to a certain extent, from the sample during the purge.TABLE 1Density of pure and purged samplesMeasure-Measure-Measure-ment 1ment 2ment 3averagestdevDensity of Pure0.790570.790630.790610.790600.00003sample 0 days[g / ml]Density Purged0.792200.792080.792150.792140.00006sample 0 days[g / ml]Gums Kinetic Formation

[0041] Sixteen vials were prepared in order to follow the gum kinetic formation. Eight vials were purged with nitrogen and eight vials were not purged. The goal was to measure the amount of gum formed after 10, 20 and 60 days. The pure samples were poured from the received Schott bottles into the small vials with no treatment. The purged samples were purged with nitrogen for 5 minutes. The vials were then closed, and paraffin film was used. At each data point time, the supernatant of the vials was emptied. The vials were left to dry in a fume hood overnight. The day after, 10 mL of tetrahydrofuran (THF) was added to the vial to solubilize the gums formed during the ageing process. The THF was then poured into pre-weighted alumina pans. THF was evaporated overnight in a fume hood. Finally, the pans were placed in a vacuum oven at 40° C. to completely remove volatiles. The gums amount formed during the ageing process at each condition was then defined by weighing the dried alumina pans.

[0042] The weight of the gum was then fitted in JMP (statistical software) to study the impact of the following factors: Type of glass (amber, transparent), Time of ageing (8, 15, 26 and 48 days), Type of treatment (pure and purged).

[0043] FIG. 5A, FIG. 5B, and FIG. 5C indicate that ageing time and treatment have a significant impact on the amount of gum being formed (P<0.05).

[0044] FIG. 6 indicates that the amount of gum increases with increased ageing time and is higher for the pure samples. The factor “type of glass” is borderline significant with a p value of 0.052.

[0045] Based on this specific ageing study, it can be concluded that gum formation is favored when the sample is not purged with nitrogen. Light also seems to increase the gum's formation rate.

[0046] In the context of the present invention, at least the following 14 embodiments are described. Embodiment 1 is a method of maintaining pyrolysis oil stability and / or quality. The method includes removing oxygen, by a physical process, from pyrolysis oil. Embodiment 2 is the method of embodiment 1, wherein the physical process comprises flowing an inert gas through the pyrolysis oil. Embodiment 3 is the method of embodiment 2, wherein the inert gas comprises: nitrogen, helium, argon, neon, carbon dioxide or combinations thereof. Embodiment 4 is the method of any of embodiments 1 to 4, wherein the pyrolysis oil is at a temperature of 20° C. to 70° C.

[0047] Embodiment 5 is a method of maintaining pyrolysis oil stability and / or quality. The method includes providing a tank for storing pyrolysis oil. The method further includes removing oxygen from the tank. The method yet further includes flowing pyrolysis oil into the tank and storing the pyrolysis oil in the tank. Embodiment 6 is the method of embodiment 5, wherein the removing of the oxygen from the tank comprises displacement with an inert gas and / or extraction with a compressor. Embodiment 7 is the method of either of embodiments 5 or 6, wherein the oxygen concentration in the tank is reduced to 0.01% to 1%. Embodiment 8 is the method of any of embodiments 5 to 7, further comprising flowing an inert gas through the pyrolysis oil to remove oxygen from the pyrolysis oil. Embodiment 9 is the method of embodiment 8, wherein the inert gas comprises: nitrogen, helium, argon, neon, carbon dioxide or combinations thereof. Embodiment 10 is the method of either of embodiments 8 or 9, wherein the pyrolysis oil is at a temperature of 20° C. to 70° C.

[0048] Embodiment 11 is a method of maintaining pyrolysis oil stability and / or quality. The method includes storing pyrolysis oil in a tank. The method further includes removing oxygen from headspace of the tank. Embodiment 12 is the method of embodiment 11, wherein the removing of the oxygen from the headspace of the tank comprises extraction by a compressor. Embodiment 13 is the method of either of embodiments 11 or 12, wherein the oxygen concentration in the tank is reduced to 0.01% to 1%. Embodiment 14 is the method of any of embodiments 11 to 13 further comprising flowing an inert gas through the pyrolysis oil to remove oxygen from the pyrolysis oil.

[0049] The systems and processes described herein can also include various equipment that is not shown and is known to one of skill in the art of chemical processing. For example, some controllers, piping, computers, valves, pumps, heaters, thermocouples, pressure indicators, mixers, heat exchangers, and the like may not be shown. All embodiments described above and herein can be combined in any manner unless expressly excluded.

[0050] Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the above disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Examples

example

Ageing Study of Pyoil Samples

[0039]Six liter samples of pyrolysis oil were collected in pre-filled nitrogen bottles. Some samples were purged with nitrogen.

Density

[0040]Density was measured on the samples at time 0, i.e., after sample preparation was completed. The data as shown in Table 1 indicates that the purging step leads to an increase of the density of the pyoil. This is because volatile constituents are being stripped, to a certain extent, from the sample during the purge.

TABLE 1Density of pure and purged samplesMeasure-Measure-Measure-ment 1ment 2ment 3averagestdevDensity of Pure0.790570.790630.790610.790600.00003sample 0 days[g / ml]Density Purged0.792200.792080.792150.792140.00006sample 0 days[g / ml]

Gums Kinetic Formation

[0041]Sixteen vials were prepared in order to follow the gum kinetic formation. Eight vials were purged with nitrogen and eight vials were not purged. The goal was to measure the amount of gum formed after 10, 20 and 60 days. The pure samples were poured fro...

Claims

1. A method of maintaining pyrolysis oil stability and / or quality, the method comprising: removing oxygen, by a physical process, from pyrolysis oil.

2. The method of claim 1, wherein the physical process comprises: flowing an inert gas through the pyrolysis oil.

3. The method of claim 2, wherein the inert gas comprises: nitrogen, helium, argon, neon, carbon dioxide, or combinations thereof.

4. The method of claim 1, wherein the pyrolysis oil is at a temperature of 20° C. to 70° C.

5. A method of maintaining pyrolysis oil stability and / or quality, the method comprising:providing a tank for storing pyrolysis oil;removing oxygen from the tank;flowing the pyrolysis oil into the tank; andstoring the pyrolysis oil in the tank.

6. The method of claim 5, wherein the removing of the oxygen from the tank comprises displacement with an inert gas and / or extraction with a compressor.

7. The method of claim 5, wherein oxygen concentration in the tank is reduced to 0.01% to 1%.

8. The method of claim 5, further comprising: flowing an inert gas through the pyrolysis oil to remove oxygen from the pyrolysis oil.

9. The method of claim 8, wherein the inert gas comprises: nitrogen, helium, argon, neon, carbon dioxide or combinations thereof.

10. The method of claim 9, wherein the pyrolysis oil is at a temperature of 20° C. to 70° C.

11. A method of maintaining pyrolysis oil stability and / or quality, the method comprising:storing pyrolysis oil in a tank; andremoving oxygen from headspace of the tank.

12. The method of claim 11, wherein the removing of the oxygen from the headspace of the tank comprises extraction by a compressor.

13. The method of claim 12, wherein oxygen concentration in the tank is reduced to 0.01% to 1%.

14. The method of claim 13 further comprising: flowing an inert gas through the pyrolysis oil to remove oxygen from the pyrolysis oil.

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